For the final instalment of the trilogy, filmmaker Todd Phillips takes a sharp left turn, abandoning the formula of the first two movies to send the Wolf Pack on a road thriller that isn't remotely funny. A few wacky moments are provided by the actors, but there isn't one punchline in the entire film. And it doesn't really work as a thriller either, since there's no real suspense.

Once again it starts in Los Angeles, where everyone has recovered from their antics in Bangkok. But Phil, Stu and Doug (Cooper, Helms and Bartha) are worried that Alan (Galifianakis) is refusing to grow up, so they hold an intervention and set out to drive him to a desert retreat. On the way, they're waylaid by mobster Marshall (Goodman), who holds Doug hostage to force the the Wolf Pack to find renegade nutcase Chow (Jeong), who has stolen Marshall's stash of gold bars. They track Chow to Mexico, but things quickly get even messier as Chow slips through their fingers. And to catch him, they'll have to return to the scene of their original adventure: Las Vegas.

There isn't much to the screenplay, which is a series of action scenes and caper-style set-pieces strung together with rapid-fire dialog and general vulgarity. But while the film is expertly shot and edited, with a solid cast and terrific settings, there simply isn't any actual humour. No one gets drunk, so there's no hangover this time. And the only amusing moments are offhanded character bits that are utterly irrelevant to the nonsensical chaos of the plot. Which kind of makes us wonder why we ever found these losers so hilarious to begin with.

There's real potential in this premise for a ripping screwball comedy anchored by two likeable actors, but the filmmakers simply don't trust the material, stirring in constant elements of action mayhem that don't work at all. Pointless car chases, over-violent fight scenes, murderous henchmen, a ruthless bounty hunter and even a full-on heist: all of these things feel like irrelevant distractions for a movie that's essentially just a remake of Planes, Trains and Automobiles, with an identity-theft twist.

Bateman plays the androgynously named Sandy Patterson, a Denver accountant struggling to make ends meet when he's offered a great new job with a colleague (Cho) that will better help him support his pregnant wife (Peet) and their two precocious daughters. Then suddenly everything is jeopardised when someone steals his identity and, for some inexplicable reason, he has to go to Florida and bring the culprit back to Denver himself. The con artist turns out to be Diana (McCarthy), who's a lot feistier than Sandy expects. And as they begin the long road trip to Colorado, he discovers that she's also being chased by two mob goons (Harris and Rodriguez) and a bounty hunter (Patrick).

Plenty of films manage to mix violence and comedy effectively, but director Gordon and writer Mazin seem to flail at every turn, wildly veering from corny sentimentality to ugly brutality, punctuated by humour that only occasionally makes us laugh. And at nearly two hours, the film feels far too long even though the pace is frenetic. The various set pieces simply don't fit in with the basic premise, leaving the plot in tatters. All of these nasty villains chasing Diana are utterly meaningless, and many of the action sequences feel both inexplicable and implausible.